Applicant is aware of U.S. Pat. No. 4,542,878 to Kulisek for a ball valve showing a portion of the ball removed and a dome-like projection on the end. Applicant is also aware of German Patent No. 2,710,519 for a rotatable plug valve showing the ball having sides flattened. None of these prior art patents show a ball valve wherein the ball has:
(1) concave sides with the concave sides terminating at their periphery in sharp edges; PA1 (2) a flow passage passing through the spherical surface of the ball at sharp edges and; PA1 (3) the valve body has a seat with an inner transition surface, an outer transition surface, and a seat surface on the flow passage through the ball and is disposed at a shallow angle to the seat surface around the flow passage.
The seat area is not affected by the edges of the concave recess, the edges around the flow passage through the ball will perform a shearing, scissor-like action for cleaning the ball. Therefore, combining the edges of the spherical concave ball face and the flowport edges the entire seat area benefits from the scissor-like cleaning effect.